Electrostatic chuck having a plurality of heater coils

ABSTRACT

An electrostatic chuck for receiving a substrate in a substrate processing chamber comprises a ceramic puck having a substrate receiving surface having a plurality of spaced apart mesas, an opposing backside surface, and central and peripheral portions. A plurality of heat transfer gas conduits traverse the ceramic puck and terminate in ports on the substrate receiving surface to provide heat transfer gas to the substrate receiving surface. An electrode is embedded in the ceramic puck to generate an electrostatic force to retain a substrate placed on the substrate receiving surface. A plurality of heater coils are also embedded in the ceramic puck, the heaters being radially spaced apart and concentric to one another.

CROSS-REFERENCE

This application is a continuation of U.S. patent application Ser. No.11/740,869, filed Apr. 26, 2007, which claims priority to U.S.Provisional Application Ser. No. 60/796,093, filed Apr. 27, 2006, bothof which are incorporated by reference herein and in their entirety.

BACKGROUND

Embodiments of the present invention relate to a substrate support forholding a substrate in a substrate processing chamber.

In the processing of substrates, such as semiconductors and displays, anelectrostatic chuck is used to hold a substrate in a substrateprocessing chamber. A typical electrostatic chuck comprises an electrodecovered by a dielectric, such as ceramic or polymer. When the electrodeis electrically charged, electrostatic charges in the electrode andsubstrate holds the substrate on the chuck. Typically, the temperatureof the substrate is controlled by providing a gas behind the substrateto enhance heat transfer rates across the microscopic gaps between thesubstrate and the surface of the chuck. The electrostatic chuck can besupported by a base which has channels for passing a fluid therethroughto cool or heat the chuck. Once a substrate is securely held on thechuck, process gas is introduced into the chamber and a plasma is formedto process the substrate by CVD, PVD, etch, implant, oxidation,nitridation, or other processes.

During processing, a substrate is often subjected to non-uniformprocessing rates or other processing properties across the substratesurface. For example, such non-uniform processing can give rise toconcentric processing bands in the radial direction across the substratesurface. Non-uniform processing can also result from the distribution ofgas species or plasma species in the chamber. For example, thedistribution of gas across the chamber can vary depending on thelocation of the inlet gas ports and exhaust ports in the chamberrelative to the substrate surface. Also, mass transport mechanisms canalter the rates of arrival and dissipation of gaseous species atdifferent regions of the substrate surface. Variability in processingrates can also arise from non-uniform heat loads occurring in thechamber. Such variable heat loads can also occur, for example, due tonon-uniform coupling of energy from the plasma sheath to the substrateor radiant heat reflected from chamber walls. Such processingvariability across the substrate is undesirable as the active andpassive electronic devices being fabricated at different regions of thesubstrate, for example, the peripheral and central substrate regions,can have different properties.

Accordingly, it is desirable to reduce the variations in processingrates and other process characteristics across the substrate surfaceduring processing. It can also be desirable to control temperatures atdifferent regions across the processing surface of the substrate. It isfurther desirable to control a temperature and gas distribution profileacross the substrate during its processing.

SUMMARY

An electrostatic chuck for receiving a substrate in a substrateprocessing chamber comprises a ceramic puck having a substrate receivingsurface having a plurality of spaced apart mesas, an opposing backsidesurface, and central and peripheral portions. A plurality of heattransfer gas conduits traverse the ceramic puck and terminate in portson the substrate receiving surface to provide heat transfer gas to thesubstrate receiving surface. An electrode is embedded in the ceramicpuck to generate an electrostatic force to retain a substrate placed onthe substrate receiving surface. A plurality of heater coils are alsoembedded in the ceramic puck, the heaters being radially spaced apartand concentric to one another.

DRAWINGS

These features, aspects, and advantages of the present invention willbecome better understood with regard to the following description,appended claims, and accompanying drawings, which illustrate examples ofthe invention. However, it is to be understood that each of the featurescan be used in the invention in general, not merely in the context ofthe particular drawings, and the invention includes any combination ofthese features, where:

FIG. 1 is a schematic sectional side view of an embodiment of anelectrostatic chuck;

FIG. 2 is a schematic bottom view of the chuck of FIG. 1;

FIG. 3 is a schematic side view of an optical temperature sensor;

FIGS. 4A and 4B are schematic perspective views of the top (FIG. 4A) andbottom (FIG. 4B) of an embodiment of a substrate support comprising abase and electrostatic chuck;

FIG. 4C is a schematic perspective top view of another embodiment of asubstrate support comprising a base and electrostatic chuck;

FIG. 4C1 is perspective detailed view of circled section 4C1 of FIG. 4C,showing a peripheral zone with a peripheral port and surrounding sealingrims;

FIG. 4D is a bottom plan view of the base of the support of FIG. 4C;

FIG. 5A is a schematic sectional side view of an embodiment of a ringassembly comprising an edge ring over a clamp ring on the substratesupport of FIGS. 4A and 4B;

FIG. 5B is a detailed view of the ring assembly of FIG. 5A;

FIG. 5C is a schematic sectional side view of another embodiment of aring assembly comprising an edge ring over a clamp ring on a substratesupport;

FIG. 6 is schematic sectional side view of an embodiment of anelectrical connector assembly of a base;

FIG. 7 is schematic sectional side view of an embodiment of an contactband; and

FIG. 8 is a schematic side view of an embodiment of a substrateprocessing chamber with the substrate support.

DESCRIPTION

An embodiment of an electrostatic chuck 20 comprises a ceramic puck 24comprising a ceramic body having a substrate receiving surface 26 thatis the top surface of the puck 24 and which serves to hold a substrate25, as shown in FIG. 1. The ceramic puck 24 also has a backside surface28 opposing the substrate receiving surface 26. The ceramic puck 24further has a peripheral ledge 29 having a first step 31 and a secondstep 33, the second step 33 being radially outward from, and lower than,the first step 31. The ceramic puck 24 comprises at least one ofaluminum oxide, aluminum nitride, silicon oxide, silicon carbide,silicon nitride, titanium oxide, zirconium oxide, and mixtures thereof.The ceramic puck 24 can be unitary monolith of ceramic made by hotpressing and sintering a ceramic powder, and then machining the sinteredform to form the final shape of the puck 24.

In one version, as shown in FIGS. 1 and 2, the backside surface 28 ofthe ceramic puck 24 comprises a plurality of spaced apart mesas 30 whichare each cylindrical mounds that are separated from each other by aplurality of gaps 32. In use, the gaps 32 are filled with a gas, such asair, to regulate the heat transfer rates from the backside surface 28 toother underlying surfaces of other structures. In one embodiment, themesas 30 comprise cylindrical mounds, which can even be shaped as posts,that extend up from the surface 28, the posts having a rectangular orcircular cross-sectional shape. The height of the mesas 30 can be fromabout 10 to about 50 microns, and the width (or diameter) of the mesas30 from about 500 to about 5000 microns. However, the mesas 30 can alsohave other shapes and sizes, for example, cones or rectangular blocks,or even bumps of varying sizes. In one version, the mesas 30 are formedby bead blasting the backside surface 28 with a bead size that issuitably small, for example, in the tens of microns, to etch away byerosion the material of the backside surface 28 to form the shaped mesas30 with the intervening gaps 32.

The ceramic puck 24 also comprises an electrode 36 embedded therein togenerate an electrostatic force to retain a substrate placed on thesubstrate receiving surface 26. The electrode 36 is a conductor, such asa metal, and be shaped as a monopolar or bipolar electrode. Monopolarelectrodes comprise a single conductor and have a single electricalconnection to an external electrical power source and cooperate with thecharged species of the overlying plasma formed in a chamber to apply anelectrical bias across the substrate held on the chuck 20. Bipolarelectrodes have two or more conductors, each of which is biased relativeto the other to generate an electrostatic force to hold a substrate. Theelectrode 36 can be shaped as a wire mesh or a metal plate with suitablecut-out regions. For example, an electrode 36 comprising a monopolarelectrode can be a single continuous wire mesh embedded in the ceramicpuck as shown. An embodiment of an electrode 36 comprising a bipolarelectrode can be a pair of filled-in C-shaped plates that face oneanother across the straight leg of the C-shape. The electrode 36 can becomposed of aluminum, copper, iron, molybdenum, titanium, tungsten, oralloys thereof. One version of the electrode 36 comprises a mesh ofmolybdenum. The electrode 36 is connected to a terminal post 58 whichsupplies electrical power to the electrode 36 from an external powersupply.

The ceramic puck 24 also has a plurality of heat transfer gas conduits38 a,b that traverse the ceramic body and terminating in ports 40 a,b onthe substrate receiving surface 26 to provide heat transfer gas to thesubstrate receiving surface 26. The heat transfer gas, which can be forexample, helium, is supplied below the substrate backside 34 to conductheat away from the overlying substrate 25 and to the receiving surface26 of the ceramic puck 24. For example, a first gas conduit 38 a can belocated to supply heat transfer gas to a central heating zone 42 a ofthe substrate receiving surface 26, and a second gas conduit 38 b can belocated to supply heat transfer gas to a peripheral heating zone 42 b ofthe substrate receiving surface 26. The central and peripheral heatingzones 42 a,b of the substrate receiving surface 26 of the ceramic puck24 allow corresponding portions of the substrate process surface 44, forexample, the overlying central and peripheral portions 46 a,b of thesubstrate 25, respectively, to be maintained at different temperatures.

The temperatures at the central and peripheral heating zones 42 a,b ofthe substrate receiving surface 26 of the ceramic puck 24 are furthercontrolled using a plurality of heater coils 50, 52, for example, afirst heater coil 50 and a second heater coil 52, embedded in theceramic puck 24. For example, the heater coils 50, 52 can be radiallyspaced apart and concentric about one another, and even side by side andin the same plane. In one version, the first heater coil 50 is locatedat a central portion 54 a of the ceramic puck 24 and the second heatercoil 52 located at a peripheral portion 54 b of the ceramic puck 24. Thefirst and second heater coils 50, 52 allow independent control of thetemperatures of the central and peripheral portions 54 a, 54 b of theceramic puck 24, and further cooperate with the mesas 30 on the backsidesurface 28 of the ceramic puck 24 to allow regulation of a temperatureprofile of a substrate 25 placed on the receiving surface 26 of theceramic puck 24.

Each heater coil 50, 52 provides the ability to independently controlthe temperatures of the heating zones 42 a,b, to achieve differentprocessing rates or characteristics across the radial direction of theprocessing surface 44 of the substrate 25. As such, differenttemperatures can be maintained at the two heating zones 42 a,b to affectthe temperatures of the overlying central and peripheral portions 46 a,bof the substrate 25, thereby counteracting any variable gas speciesdistribution or heat load occurring during processing of the substrate25. For example, when gas species at the peripheral portion 46 b of theprocessing surface 44 of the substrate 25 are less active than those atthe central portion 46 a, the temperature of the peripheral heating zone42 b is elevated to a higher temperature than the central heating zone42 a to provide a more uniform processing rates or processcharacteristics across the processing surface 44 of the substrate 25.

In one version, the first and second heater coils 50, 52 each comprisecircular loops of resistive heating elements that are arranged side byside, and can even be substantially in the same plane. For example, theheater coils 50, 52 can each be a continuous concentric loop thatgradually spirals radially inward in the body of the ceramic puck 24.The heater coils 50, 52 can also be spiral coils that spiral about anaxis passing through the center of the coils, for example, like a lightbulb filament, which are positioned in concentric circles across theinside volume of the ceramic puck 24. The resistive heating elements canbe composed of different electrically resistive materials, such as forexample, molybdenum. In one version, the heater coils 50, 52 eachcomprise an electrical resistance sufficiently high to maintain thesubstrate receiving surface 26 of the ceramic puck 24 at temperatures offrom about 80 to about 250° C. In this version, the electricalresistance of the coils are from about 4 to about 12 Ohms. In oneexample, the first heater coil 50 has an electrical resistance of 6.5ohm and the second heater coil 52 has an electrical resistance inner of8.5 ohm. The heater coils 50, 52 are powered via independent terminalposts 58 a-d which extend through the ceramic puck 24.

In conjunction with the heater coils 50, 52, the pressure of heattransfer gas can also be controlled in the two zones 42 a,b to renderthe substrate processing rates more uniform across the substrate 25. Forexample, the two zones 42 a,b can each be set to hold heat transfer gasat a different equilibrated pressure to provide different heat transferrates from the backside 34 of the substrate 25. This is accomplished bysupplying heat transfer gas at two different pressures through the twoconduits 38 a, 38 b, respectively, to exit at two different locations ofthe substrate receiving surface 26.

The electrostatic chuck 20 can also include optical temperature sensors60 a,b that pass through holes 62 a,b in the ceramic puck 24 to contactand accurately measure the temperatures of the overlying central andperipheral portions 46 a,b of the substrate 25. A first sensor 60 a ispositioned at the central heating zone 42 a of the ceramic puck 24 toread the temperature of the central portion 46 a of the substrate 25,and a second sensor 60 b is positioned at the peripheral heating zone 42b of the ceramic puck 24 to correspondingly read the temperature at theperipheral portion 46 b of the substrate 25. The optical temperaturesensors 60 a,b are positioned in the chuck 20 so that the tips 64 a,b ofthe sensors lies in a plane with the substrate receiving surface 26 ofthe ceramic puck 24, such that the sensor tips 64 a,b can contact thebackside 34 of the substrate 25 held on the chuck 20. The legs 66 a,b ofthe sensors 60 a,b extend vertically through the body of the ceramicpuck 24.

In one version, as shown in FIG. 3, each optical temperature sensor 60comprises a heat sensor probe 68 comprising a copper cap 70 shaped as aclosed off cylinder with a side 72 and a dome-shaped top 74 that servesas the tip 64. The copper cap 70 can be composed of oxygen free coppermaterial. A phosphorous plug 76 is embedded inside, and in directcontact with, the top 74 of the copper cap 70. The phosphorous plug 76embedded in the copper cap 70 provides quicker and more sensitivethermal response for the heat sensing probe 68. The tip 64 of the coppercap 70 is a dome-shaped top 74 to allow repeated contact with differentsubstrates 25 without eroding or damaging the substrates. The copper cap70 has a recessed groove 78 for receiving epoxy 79 to affix the cap 70in the sensor probe 68.

The phosphorous plug 76 converts heat in the form of infrared radiationto photons which are passed though an optical fiber bundle 80. Theoptical fiber bundle 80 can be composed of borosilicate glass fibers.The optical fiber bundle 80 is encased by a sleeve 82, which in turn ispartially surrounded by a temperature isolation jacket 84 that serves toisolate the temperature sensor from the heat of the base that supportsthe ceramic puck. The sleeve 82 can be a glass tubing to provide betterthermal insulation from the surrounding structure, but can also be madefrom a metal such as copper. The temperature isolation jacket 84 may becomposed of PEEK, a polyetheretherketone, and can also be Teflon®(polytetrafluoroethylene) from Dupont de Nemours Co. Delaware.

A substrate support 90 comprises the electrostatic chuck 20 secured to abase 91 which is used to support and secure the chuck 20, as shown inFIGS. 4A, 4B and 5A. The base 91 comprises a metal body 92 with a topsurface 94 having a chuck receiving portion 96 and peripheral portion98. The chuck receiving portion 96 of the top surface 94 is adapted toreceive the backside surface 28 of the ceramic puck 24 of theelectrostatic chuck 20. The peripheral portion 98 of the base 91 extendsradially outward beyond the ceramic puck 24. The peripheral portion 98of the base 91 can be adapted to receive a clamp ring 100 which can besecured to the top surface of the peripheral portion of the base. Themetal body 92 of the base 91 has a number of passages 102 running from abottom surface 104 of the base to the top surface 94 of the base 91, tofor example, hold the terminals 58 a-d or feed gas to the gas conduits38 a,b of the ceramic puck 24.

The chuck receiving portion 96 of the top surface 94 of the base 91comprises one or more grooves 106 a,b to retain and flow air across thebackside of the ceramic puck 24. In one embodiment, the chuck receivingportion 96 comprises a peripheral groove 106 a which cooperates with aplurality of mesas 30 on the backside surface 28 of a ceramic puck 24 tocontrol a rate of heat transfer from the peripheral portion 54 b of theceramic puck 24. In another embodiment, a central groove 106 b is usedin conjunction with the peripheral groove 106 a to regulate heattransfer from the central portion 54 a of the ceramic puck 24.

The grooves 106 a,b in the top surface 94 of the base 91 cooperate withthe mesas 30 on the backside surface 28 of the ceramic puck 24 tofurther regulate the temperatures across the substrate processingsurface 44. For example, the shape, size, and spacing of the mesas 30control the total amount of contact surface of the mesas 30 with the topsurface 94 of the base 91 thereby controlling the total heat conductionarea of the interface. For example, the mesas 30 can be shaped and sizedso that only 50% or less, for example 30%, of the total area of thebackside surface 28 of the ceramic puck 24 actually contacts the topsurface 94 of the base 91. The less the contact area, the higher thetemperatures across the substrate processing surface 44. Also, air isprovided between the mesas 30 and across the backside surface 28 toserve as a further temperature regulator.

The mesas 30 on the backside surface 28 of the ceramic puck 24 can bedistributed across the backside surface 28 in a uniform or non-uniformpattern. In a uniform pattern, the distance between the mesas 30 asrepresented by the gaps 32 remain substantially the same, and in anon-uniform spacing the gaps distance varies across the surface 28. Theshape and size of the mesas 30 can also be made to vary across thesurface 28. For example, a non-uniform pattern of mesas 30 can bearranged to provide different amounts of contact surface across thebackside surface 28 of the ceramic puck 24 at different regions, tocontrol the heat transfer rates from the central and peripheral portions54 a,b, respectively, of the puck 24, and thus, the temperatures at thecentral and peripheral portions 46 a,b of the overlying substrate 25.

The base 91 further comprises a plurality of channels 110 forcirculating a fluid, such as water. The base 91 with the circulatingcooling fluid serves as a heat exchanger to control the temperatures ofthe chuck 20 to achieve desired temperatures across the processingsurface 44 of the substrate 25. The fluid passed through the channels110 can be heated or cooled to raise or lower the temperature of thechuck 20 and that of the substrate 25 held on the chuck 20. In oneversion, the channels 110 are shaped and sized to allow fluid to flowthrough to maintain the base 91 at temperatures of from about 0 to 120°C.

The base 91 further comprises an electrical terminal assembly forconducting electrical power to the electrode 36 of the electrostaticchuck 20. The electrical terminal assembly comprises a ceramic insulatorjacket 124. The ceramic insulator jacket 124 can be for example,aluminum oxide. A plurality of terminal posts 58 are embedded within theceramic insulator jacket 124. The terminal posts 58, 58 a-d supplyelectrical power to the electrode 36 and heater coils 50, 52 of theelectrostatic chuck 20. For example, the terminal posts 58 can includecopper posts.

The contact bands 140 are configured to surround the terminal posts 58,58 a-d, of the electrical terminal assembly, as shown in FIG. 7. Eachcontact band 140 comprises metal, such as, for example, a copper alloy.The structural body of the contact band 140 comprises a casing 142adapted to fit around a terminal post 58. The shape of the casing 142 isdependent upon the shape of the post 58 and optimally, should mimic theshape of the post 58. A portion or a strip 146 of the casing 142comprises a band 144 with a plurality of slots 148 and a plurality ofheat transfer louvers 150; the slots 148 configured in a pattern toconsequently create the louvers 150 alternating with the slots 148. Inone embodiment, the plurality of slots 148 and louvers 150 extend from atop edge 152 of the strip 146 to the bottom edge 154 of the strip 146 ora portion of the casing 142. The plurality of slots 148 and louvers 150create a spring-like characteristic reducing the stiffness of the casing142 and allowing it to conform around the outside surface of theterminal post 58 or terminal. The configuration of the plurality ofslots 148 on the strip 146 of the casing 142 also, through itsspring-like characteristics, causes the terminal post 58 to be incontact with substantial regions of the inner exposed surfaces 143 ofthe casing 142. This allows for optimal heat transfer between thecontact band 140 and the terminal.

A ring assembly 170 can also be provide to reduce the formation ofprocess deposits on, and protect from erosion, peripheral regions of thesubstrate support 90 comprising the electrostatic chuck 20 supported bythe base 91, as shown in FIG. 5A. In the embodiment shown in FIG. 5B,the ring assembly 170 comprises a clamp ring 100 comprising an annularbody 171 having holes 175 that are secured to the peripheral portion 98of the top surface 94 of the base 91 with securing means such as screwsor bolts 169. The clamp ring 100 has an upper lip 172 which extendsradially inward from a top surface 174 and an outer side surface 176which forms the radially outer perimeter of the clamp ring 100. The lip172 has an undersurface 173 which is sized to fit and rest on the firststep 31 of the peripheral ledge 29 of the ceramic puck 24. In oneversion, the lip 172 has an undersurface 173 which is adapted to form agas-tight seal between the ceramic puck 24 and the base 91. For example,the undersurface 173 can comprise a polymer, such as a polymer layer,for example polyimide, to form a good seal. The clamp ring 100 isfabricated from a material that can resist erosion by plasma, forexample, a metallic material such as stainless steel, titanium oraluminum; or a ceramic material, such as aluminum oxide.

The ring assembly 170 also includes an edge ring 180 comprising a band182 having a foot 184 which rests on the top surface 174 of the clampring 100 as shown in FIG. 5B. The edge ring 180 also has an annularouter wall 186 enclosing the outer side surface 176 of the clamp ring100 which would otherwise be exposed to the processing environment toreduce or prevent deposition of sputtering deposits on the clamp ring100. The edge ring 180 also has a flange 190 covering the second step 33of the peripheral ledge 29 of the ceramic puck 24. The flange 190comprises a projection 194 that terminates below an overhanging edge 196of the substrate 25. The flange 190 defines an inner perimeter of theedge ring 180 that surrounds the periphery of the substrate 25 toprotect regions of the ceramic puck 24 that are not covered by thesubstrate 25 during processing. The clamp ring 100 and the edge ring 180of the ring assembly 170 cooperate to reduce the formation of processdeposits on, and protect from erosion, the electrostatic chuck 20supported on the base 91 during the processing of a substrate 25. Theedge ring 180 also protects the exposed side surfaces of the substratesupport 90 to reduce erosion in the process. The ring assembly 170 canbe easily removed to clean deposits from the exposed surfaces of theclamp ring 100, and edge ring 180, so that the entire substrate support90 does not have to be dismantled to be cleaned. The edge ring 180 canbe made from a ceramic, such as for example, quartz.

Another version of the ring assembly 170 that can reduce the formationof process deposits on, and protect from erosion, the substrate support90 comprising the electrostatic chuck 20 and base 91, is shown in FIG.5C. In this version, the clamp ring 100 comprises an annular body 171having a top surface 174 for supporting an edge ring 180 and a bottomsurface 192 with a plurality of holes 175 adapted to be secured to theperipheral portion 98 of the top surface 94 of the base 91. The annularbody 171 is secured to the peripheral portion 98 of the top surface 94of the base 91 by screws or bolts 169 that mate with the holes 175. Theclamp ring 100 also has an upper lip 172 that extends radially inward torest on the first step 31 of the peripheral ledge 29 of the ceramic puck24. The upper lip 172 of the clamp ring 100 can also have a downwardlyprojecting bump 192 that rests on the first step 31 of the peripheralledge 29 of the ceramic puck 24 to minimize contact area, and downwardlyprojecting bump 193 extending out from a radially outward bottom recess194. The upper lip 172 of the clamp ring 100 comprises an undersurface173 which rests on the first step 31 of the peripheral ledge 29 of theceramic puck 24, and this undersurface 173 comprises, in one version, apolymer, such as a layer of polymer, for example, a polyimide. Theundersurface 173 can also be the surface of the bump 193, for example,the bump 193 can be made of the undersurface material. The outer portion194 of the clamp ring 100 comprises a radially outer side surface 176which is flat and terminates at an outer diameter 196 of the base 91.The clamp ring 100 also has a foot 197 which extends downward from theradially outer side surface 176 to rest on the peripheral portion 98 ofthe top surface 94 of the base 91. The clamp ring 100 can be made from ametal such as aluminum, titanium or stainless steel; or a ceramic, suchas aluminum oxide.

The version of the edge ring 180 shown in FIG. 5C, comprises a band 182which is wedge-shaped with an inclined upper surface 183. A lowersurface 185 of the band 182 covers the top surface 174 of the clamp ring100. The edge ring 180 also has an inner flange 187 that extendsradially inward from the wedge-shaped band 182. The inner flange 187comprises a bottom surface 188 that is stepped up in relation to thelower surface 185 of wedge-shaped band 182. The inner flange 187 alsohas a foot 189 that can rest on the first step 33 of the peripheralledge 29 of the ceramic puck 24. The inner flange 187 further comprisesan upper surface 191 which has a radially inward perimeter comprising anupper step 232 and a lower step 234. The upper and lower steps 232, 234,step down in height along the radially inward direction. The innerflange 187 also has a curved edge 236 that joins to the inclined uppersurface 183 of the wedge-shaped band 182. An outer flange 238 of theedge ring 180 extends radially outward from the wedge-shaped band 182.The outer flange 238 comprises a radially inward facing surface 240 thatcovers the outer side surface 176 of the clamp ring 100. The outerflange 238 further has a bottom wall 242 that extends downwardly inrelation to the lower surface 185 of wedge-shaped band 182. The outerflange 238 also has a slanted perimeter edge 244 which reduces erosionof this region. The edge ring 180 can also be made from a ceramic, suchas quartz.

Another embodiment of the electrostatic chuck 20 comprises a ceramicpuck 24 with a substrate receiving surface 26, as shown in FIGS. 4C and4C1. The substrate receiving surface 26 comprises a pattern of grooves250 comprising radial arms 252 and circular arms 254 which areinterconnected to one another. In between these grooves 250 are raisedplateaus 256 of spaced apart mesas 258. In the version shown, the raisedplateaus 256 have an arcuate side edge 257 and are generally triangularor trapezoid shaped. However, the raised plateaus 256 can also haveother shapes and can be distributed across the substrate receivingsurface 26 in a non-symmetrical pattern. Each raised plateau 256 isdefined by a plurality of mesas 258 that can, for example, number fromabout 10 to about 1000 mesas. In one version, the mesas 258 are raisedcylindrical bumps, for example, shaped as cylinders or arcuateprojections. For example, the mesas 258 can be cylinders having averagediameters of from about 5 to about 50 microns and heights of from about0.5 to about 5 mm. The mesas 258 are provided in a shape, size, andspatial distribution across the surface 26 to control the contact areawith the overlying substrate to regulate heat transfer rates from thesubstrate to different regions of the ceramic puck 24.

A plurality of heat transfer gas conduits 38 a,b (see FIG. 1) traversethrough the ceramic puck 24 and terminate in one or more central ports40 a and peripheral ports 40 b located in the pattern of grooves 250 onthe substrate receiving surface 26. The central and peripheral ports 40a,b are capable of providing heat transfer gas to a central zone 42 aand a peripheral zone 42 b, respectively, of the substrate receivingsurface 26. The peripheral ports 40 b terminate in the arcuate cut-outs259 which are surrounded by a radially inner gas sealing rim 260 and aradially outer gas sealing rim 262 to define the peripheral zone 42 b.The central ports 40 a can terminate at intersections of the centralarms 252 and radial arms 254 of the grooves 250 to define a regioncorresponding to the central zone 42 a. The central and peripheralheating zones 42 a,b of the substrate receiving surface 26 of theceramic puck 24 allow corresponding overlying central and peripheralportions 46 a,b of the substrate 25, respectively, to be maintained atdifferent temperatures (FIG. 8).

In this version, the ceramic puck 24 has a backside surface 28 (notshown) opposing the substrate receiving surface 26 which can be planarand absent mesas, or which can have mesas previously described. Theceramic puck 24 also has a peripheral ledge 29 having a first step 31and a second step 33, the second step 33 being radially outward from,and lower than, the first step 31. The ceramic puck 24 is made fromaluminum oxide, aluminum nitride, silicon oxide, silicon carbide,silicon nitride, titanium oxide, zirconium oxide, or mixtures thereof;by hot pressing and sintering a ceramic powder and machining thesintered ceramic form to form the final shape of the puck 24. Thegrooves 250, mesas 258, gas conduits 38 a,b and ports 40 a,b, and otherstructures are machined into the ceramic structure.

In the version shown in FIG. 4D, the base 91 comprises a metal body 92with a top surface 94 (not shown) having a chuck receiving portion 96and a peripheral portion 98 which extends radially outward beyond theceramic puck 24. In this version, the base 91 comprises a single channel110 for circulating a fluid, such as water, to serve as a heatexchanger. The fluid circulating channel 110 comprises a serpentinechannel which has a plurality of curved hump regions 260 a-c which aredistributed non-uniformly or asymmetrically across the base 91. Agreater length of the channel 110 is provide to pass through or acrossthose regions of the base 91 which get hotter in use, and a shorterlength is used at the cooler regions of the base 91. The resultantasymmetric fluid circulating channel 110 controls the fluid flow tomaintain uniform temperatures across the base 91.

The substrate support 90 comprising the electrostatic chuck 20 and thebase 91, can be used in a substrate processing apparatus 200, andexemplary version of which is illustrated in FIG. 8. The apparatus 200comprises a chamber 201 comprising enclosing walls 202, and in oneversion, the chamber 201 is a DPS Advantage Chamber. A gas source 204provides a process gas to the chamber through gas holes 203, the processgas being capable of processing the substrate 25, such as an etchinggas, for example, a halogen-containing gas such as chlorine or hydrogenchloride; or a deposition gas, such as a CVD or PVD gas, for example, agas for depositing dielectric or semiconducting materials. A gasenergizer 208 is provided to capacitively or inductively couple RFenergy to the process gas respectively, or transmit microwave energyinto the process gas (not shown), to form an energized gas to processthe substrate 25. For example, the process gas can be energizedcapacitively by applying an RF voltage to the electrode 36 of theelectrostatic chuck 20 via an electrode power supply 230 andelectrically grounding a wall 202 of the chamber 201. The electrodepower supply 230 also provides a DC chucking voltage to charge theelectrode 36 of the chuck 20 to electrostatically hold the substrate 25.The process gas can also be energized by coupling inductive energy tothe process gas via the inductor coil 205. Alternatively, the processgas can be energized by coupling microwave energy to the process gas viaa microwave conduit in a remote chamber (not shown). The substrate 25 isheld in the chamber 201 on a receiving surface 26 of the electrostaticchuck 20, which in turn rests on the base 91.

The chamber is controlled by a controller 212 which typically comprisesas a computer having a central processing unit (CPU), such as a Pentiumprocessor commercially available from Intel Corporation, Santa Clara,Calif., coupled to a memory and peripheral computer components. Thememory may include a removable storage, such as a CD or floppy drive; anon-removable storage, such as a hard drive; and random access memory(RAM). The controller 212 may further comprise a hardware interfacecomprising analog or digital input and output boards, and motorcontroller boards. An operator can communicate with the chambercontroller 212 via a display or data input device. To select aparticular screen or function, the operator enters the selection usingthe data input device, such as a keyboard or light pen.

The controller 212 also comprises a computer-readable program stored inthe memory, comprising program code capable of controlling andmonitoring the processes conducted in the chamber 201. Thecomputer-readable program may be written in any conventionalcomputer-readable programming language. Suitable program code is enteredinto single or multiple files using a conventional text editor andstored or embodied in computer-usable medium of the memory. If theentered code text is in a high level language, the code is compiled, andthe resultant compiler code is then linked with an object code ofpre-compiled library routines. To execute the linked, compiled objectcode, the user invokes the object code, causing the CPU to read andexecute the code to perform the tasks identified in the program. Theprogram can include a temperature control instruction set to control thetemperatures at different regions of the substrate 25, by for example,independently applying different electrical power levels to the firstand second heater coils 50, 52 in the ceramic puck 24 of the chuck 20,adjust the flow of heat transfer gas through the conduits 38 a,b andcontrolling the flow rate of fluid through the channels 110 of the base91. A process feedback control instruction set can serve as a feedbackcontrol loop between a temperature monitoring instruction set whichreceives temperature signals from the optical temperature sensors 60 a,bto adjust the power applied to the chamber components, such as theheater coils 50, 52, flow of heat transfer gas through the conduits 38a,b, and flow of fluid through the channels 110 of the base 91. Whiledescribed as separate instruction sets for performing a set of tasks,each of these instruction sets can be integrated with one another or maybe over-lapping; thus, the chamber controller 212 and thecomputer-readable program described herein should not be limited to thespecific version of the functional routines described herein.

Although the present invention has been described in considerable detailwith regard to certain preferred versions thereof, other versions arepossible. For example, the substrate support can be used for otherchambers and for other processes, than those described herein.Therefore, the appended claims should not be limited to the descriptionof the preferred versions contained herein.

1. An electrostatic chuck for receiving a substrate in a processchamber, the chuck comprising: (a) a ceramic puck comprising a substratereceiving surface having a plurality of spaced apart mesas, an opposingbackside surface, and central and peripheral portions; (b) a pluralityof heat transfer gas conduits traversing the ceramic puck andterminating in ports on the substrate receiving surface to provide heattransfer gas to the substrate receiving surface; (c) an electrodeembedded in the ceramic puck to generate an electrostatic force toretain a substrate placed on the substrate receiving surface; and (d) aplurality of heater coils embedded in the ceramic puck, the heatersbeing radially spaced apart and concentric to one another.
 2. A chuckaccording to claim 1 wherein the heater coils include a first heatercoil located at the peripheral portion of the ceramic puck and a secondheater coil located at the central portion of the ceramic puck.
 3. Achuck according to claim 1 wherein the heater coils are arranged side byside and substantially in the same plane.
 4. A chuck according to claim1 wherein the heater coils each comprise at least one of (i) a resistiveheating element comprising molybdenum; and (ii) an electrical resistancesufficiently high to maintain the substrate receiving surface of theceramic puck at temperatures of from about 80 to about 250° C.
 5. Achuck according to claim 1 wherein the ceramic puck is composed of atleast one of aluminum oxide, aluminum nitride, silicon oxide, siliconcarbide, silicon nitride, titanium oxide, zirconium oxide, and mixturesthereof.
 6. A chuck according to claim 1 wherein the ceramic puckcomprises a peripheral ledge to receive a clamp ring that forms a sealaround the ceramic puck.
 7. A chuck according to claim 1 wherein themesas on the substrate receiving surface are arrange to form a pluralityof raised plateaus which are separated by grooves.
 8. A chuck accordingto claim 7 wherein the mesas comprise at least one of (i) from about 10to about 1000 mesas; (ii) an average height of from about 5 to about 50microns; and (iii) an average diameter of from about 0.5 to about 5 mm.9. A chuck according to claim 1 wherein the backside surface furthercomprises backside mesas.
 10. A chuck according to claim 1 wherein theheater coils are independently controllable.
 11. A chuck according toclaim 1 wherein the first and second heater coils are arranged side byside and substantially in the same plane.
 12. A ring assembly for theelectrostatic chuck of claim 1 supported by a base in a substrateprocess chamber, the ceramic puck having a peripheral ledge having firstand second steps, and the base having a top surface with a chuckreceiving portion and a peripheral portion extending beyond theelectrostatic chuck, the ring assembly comprising: (a) a clamp ringcomprising (i) a top surface, (ii) an upper lip that extends radiallyinward from the top surface to rest on the first step of the peripheralledge of the ceramic puck, and (iii) an outer side surface which forms aradially outer perimeter; and (b) an edge ring comprising a band havinga foot resting on the top surface of the clamp ring, an annular outerwall enclosing the outer side surface of the clamp ring, and a flangecovering the second step of the peripheral ledge of the ceramic puck,whereby the clamp ring and the edge ring cooperate to reduce theformation of process deposits on the electrostatic chuck during theprocessing of a substrate.
 12. An assembly according to claim 12 whereinthe edge ring comprises a ceramic.
 13. An assembly according to claim 12wherein the ceramic comprises quartz.
 14. An assembly according to claim12 wherein the clamp ring comprises a metal or ceramic.
 15. An assemblyaccording to claim 14 wherein the clamp ring comprises holes that aresecured to a peripheral portion of the top surface of the base to form agas-tight seal.
 16. A base for supporting the electrostatic chuck ofclaim 1 in a substrate process chamber, the base comprising: (a) a metalbody having a top surface comprising (i) a chuck receiving portion toreceive the backside surface of the ceramic puck and comprising aperipheral groove, and (ii) a peripheral portion extending beyond theceramic puck; (b) a plurality of heat transfer gas passages forsupplying heat transfer gas to the heat transfer gas conduits in theceramic puck; (c) at least one fluid channel in the metal body forcirculating fluid therein; and (d) an electrical terminal assembly forconducting electrical power to the electrode of the electrostatic chuck.17. A base according to claim 16 wherein the electrical terminalassembly comprises a ceramic insulator jacket having embedded therein aplurality of terminal posts for supplying electrical power to theelectrode and heater coils of the electrostatic chuck, each terminalpost surrounded by a contact band comprising a metal and having aplurality of heat transfer louvers.